SPOILER ALERT: This blog is for people watching season three of The Walking Dead on FX. Don't read on if you haven't seen episode three – and if you've seen later episodes, please do not leave spoilers.

'Walk With Me'

A gutsy move this week, one that really pays off. Not many shows can ditch all the central cast for a week – not counting Andrea, who was separated from the main bunch at the end of last season. Besides, she wasn't really the centre of attention tonight. But this show is led slightly more by situation than by characters and we went some way towards finding out about a very different way of survival than the running raids Rick and his gang had been committing. After the first two weeks, Rick's lot are probably enjoying a bit of a rest, cleaning all the blood from the walls and burning corpses (or in Carol's case operating on them). We don't need to see all that. There is plenty new to contend with, such as the long-awaited arrival of Michonne (after a great but brief intro in episode one) and the Governor. Oh, and the return of lovable redneck racist, Merle Dixon.

Michonne

She has always been a firm favourite with the comic-book crowd, but then with her incredible terseness, katana sword and zombie baggage-carriers, she has always been the most comic-bookish of characters. Michonne (Danai Gurira) isn't the sort of extreme badass you can introduce into a story like this on day one – she would tip the whole mood of the show. But we're now in a well-established world and 10 months into the zombie apocalypse, so such a character seems perfectly natural. We don't know her backstory yet, but it's safe to assume she wasn't always quite like this: a zombie apocalypse necessitates a little self-reinvention (see also The Governor). She seems better equipped for it than most, maintaining a mistrust of strangers where chatty Andrea almost immediately drops her guard. And she is not at all happy about having her sword taken away. It was fun that she and Andrea had no idea that simply dying means you are a zombie; you don't have to be bitten. She had also gleaned some useful zombie survival tips such as using her baggage-carriers' scent for camouflage and realising how to rid them of their gut-munching urges. So far they're doing a great job with her, she's really living up to her potential. And now we all know how to say her name properly.

The Governor

David Morrissey is a nice bit of casting here, giving some ambiguity to the role. It is not until the closing few minutes that his malevolence is made crystal-clear. And he's another Brit on the set, which must be nice for Andrew Lincoln. I can't wait until they meet and their US accents do battle. Up until the end it was entirely possible that the Governor was a good leader and provider, stern but fair – but killing off the National Guardsmen then kicking back with a glass of booze in a room decorated with zombie heads in water tanks shows there's plenty wrong here. And note the way he tips his glass into something offscreen: there's more to that gesture too (if you've read the comics, please keep quiet on this, and everything else spoilerific for that matter). Also, there is not so much as a hint to his backstory or what he has done to get where he is. He's expert at keeping his cards very close to his chest, dismissing his title as a nickname, but even the fairly gormless Andrea saw through that one. As with most things, if it appears too good to be true, then it usually is. That's certainly true of the community of Woodbury with its curfew and armed guards.

Merle

It's good to see Merle back, and not in a dream this time. I've been a long-time fan of Michael Rooker since his still-stunning movie debut in Henry: Portrait of a Serial Killer and few actors can manage the mix of terrifying and pathetic as well as he can. He seems to be behaving himself in Woodbury, but then so did the Governor. Merle still has some scores to settle, and when the show brings both groups together there'll be plenty to deal with, as he will be reunited with his far nicer brother Daryl, and Rick, who cuffed him and left him on a rooftop – resulting in his Evil Dead 2-style stump. That's not even considering how Rick and the Governor are going to get along (or, more likely, not).

Zombie of the Week

Some good ones to choose from: there was a classic bisected zombie in the helicopter wreckage and, of course, the Governor's bizarre aquarium of heads, but the prize goes to Michonne's multipurpose zombie pets, to whom we sadly had to say goodbye. Their missing arms and jaws were rendered using a great combination of practical makeup effects and CGI, so they were probably just too expensive to have around for long.

So, next week, back to prison or stay in Woodbury? Surely now we can handle cutting between both. We shall see. One thing is clear, the show has proved it can expand its scope easily without sacrificing pace or tension. It hasn't put a foot wrong this time around and this season really is shaping up into something great.

Phelim O'Neill's episode blog: We're building towards a big finish, and it's all kicking off. Before we anticipate next week's season finale, let's pause to reflect on the sad demise of Merle – an unforgettable character, well played